NATIONAI. ACADEMY OF SCIENCES. 


VO 11,. III. 

FIFTEENTH MEMOIR. 

ON THE SYNCARIDA, A HITHERTO UNDESCRIBED SYNTHETIC GROUP 
OF EXTINCT MALACOSTRACOUS CRUSTACEA. 








NATIONAL ACADEMY OF SCIENCES. 

VOX.. IIT. 

FIFTEENTH MEMOIR 

ON THE SYNCARIDA, A HITHERTO DNDESCRIBED SYNTHETIC GROUP 
OF EXTINCT MALACOSTRACOUS CRUSTACEA. 



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I.-ON THE SYNCARIDA, A HITHERTO CNDESCRIBED SYNTHETIC GROUP 
OF EXTINCT MALACOSTRACOUS CRUSTACEA. PLS. I, II. 

READ APRIL 21, 1885. 


By a. S. Packaed. 


For a long time I have been desirous of examining into the relationship of the singular group of 
Carboniferous Crustacea represented by the genus Acauthotelson of Messrs. Meek and Worthen, as 
it has seemed to be a remarkable connecting link between the Edriophthalmata (or Tetradecapoda) 
and the Decapoda (in the older sense). An unexpected opportunity has been offered in a large 
series of specimens, which, without solicitation on my part, has been generously offered me by 
E. D. Lacoe, esq., of Pittston, Pa., and J. C. Carr, esq., of Morris, Ill. Mr. Lacoe’s collection was 
a very rich one, comprising over forty nodules, each containing a usually well-preserved Acantho- 
telsou. Although additional specimens are much to be desired, especially such as may show the 
eyes and their nature, whether sessile or stalked, a point still unknown, the eyes not having been 
with certainty identified, and also to better show the nature of the abdominal appendages, it seems 
"to us that enough characters have been preserved to allow us to present a tolerably accurate 
account of the essential features of the group. 

The genus Acauthotelson was first proposed by Messrs. Meek and Worthen, in 1860, ^ and the 
species described as A. stimpsoni M. W. A second species, A. eveni, was described by the same 
authors in 1868. ^ Additional facts were stated and figures given in the Report of the Geological 
Survey of Illinois, III, Paleontology, 1868. The specimens we possess enable us to amend and to 
add to their original descriptions; but in doing so we wish to bear witness to the care and ability 
displayed by the authors in the examination and illustrations of this form. The genus is referred 
with doubt by the authors to the Isopoda, who also refer to its resemblance to some of the lower 
types of macroural Decapods. They remark : “ From all the specimens of this genus now known 
it is evident that, in the nature of its anteume, as well as in the forward direction of all its thoracic 
legs, and to some extent even in the nature of its caudal appendages, it differs from the Tetra¬ 
decapoda, and approaches some of the lower types of the macroural Decapoda. In the possession 
of seven distinct thoracic segments, without a carapax, however, as well as in the form of all its 
thoracic and abdominal segments, it agrees with the Tetradecapoda, particularly with the Isopoda, 
which have but one pair of the abdominal appendages styliform, instead of three, as in the 
Amphipoda. One specimen of A. stimpsoni (represented by fig. B, p. 549) also appears to show 
the eyes (marked I in the cut) to be sessile, though remarkably prominent. If they are sessile, this 
must be conclusive evidence that it must be a Tetradecapod. Until other examjiles, showing more 
clearly the nature of its eyes and some other parts, can be examined, we leave it provisionally 
where we first placed it with doubt, in the Isopod group of the Tetradecapoda.” (P. 550.) 

The following description, while embracing the more general characteristics of the group to 


1 Proceedings Academy of Natural Sciences, Philadelphia. 
* Amer. Jonru. Sc., 2d ser., xlvi, 28, 1868. 







124 


MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 


which Acanthotelson belongs, also without doubt comprises the generic and specific characters. 
We will first give a description of the fossils themselves, based on the material we have had for 
examination, and then endeavor to point out those characters which we suppose to be the essential 
features of the group to which the genus belongs, and also to indicate the probable affinities to 
the other divisions or suborders of Malacostraca. It may be as well to say that, after examining 
some forty specimens, we are unable to distinguish between Acanthotelson stinipsoni and event, and 
are inclined to believe that the former is the young of the latter species. 

In Mr. Lacoe’s No. 501& the head is well preserved; the first arthromere or segment is considerably 
shorter than any of the succeeding ones; it is slightly less than two-thirds as long as the succeed¬ 
ing arthromere; it bears in front a well-marked, small, triangular rostrum, wffiich is acute at the 
tip, and is about two-thirds as long as the segment itself; the edge of the rostrnm is considerably 
raised, especially at the base. The front edge of the segment on each side of the rostrum is also 
margined with an elevated ridge. The surface of the segment is rather full and convex on each 
side, but not so decidedly so as the second segment. The second arthromere is about as long as 
those succeeding, though not quite so long as the sixth arthromere; on each side is a low boss-like 
swelling, situated obliquely, and prolonged in an oblique direction to the anterior outer edge. 
The second segment is distinctly separated by an impressed line from the first, but there is not a 
true articulation between them, so that the first and second cephalic segments may be said to be 
consolidated and to represent the carapace of the Schizopoda. The three succeeding segments 
have a transverse, uninterrupted, smooth ridge situated in the middle on the third, but in the fifth 
segment near the hind margin. The sixth and succeeding segments are smooth and even. The 
body is of even width to near the telsou. The lower edges of the segments are evenly rounded, 
those of the hinder abdominal segments are more acutely rounded. 

We have been unable to detect any positive traces of the eyes, nor can we state whether they 
were sessile or stalked, though if they were present and sessile we do not see why they should not 
have been preserved in some of the specimens (particularly 501* and 40G*).^ 

The first pair of anteunm seem to arise directly from each side of the small, short, rudimentary 
rostrum. The scape is three-jointed, and not very long and slender; second joint not so thick, 
and about one fourth shorter than the first and twice as long as thick ; third joint long and slender, 
considerably longer than the second. The scape bears two fiagella, which are long, slender, mul- 
tiarticulate branches of unequal length, of which the inner is the thicker and shorter, the outer 
flagellum much slenderer and longer, the entire length of the antenme being one-half that of the 
second or outer pair. The second pair of anteniife have also a three-jointed scape (which is not 
accurately represented in Meek and Wortheu’s figure). The basal joint is short; second joint shorter 
than the first, with two unequal internal spines; third joint slightly longer than the second and 
much smaller; there are traces of a small antennal scale; the flagellum is long and slender, its 
entire length about half that of the body. 

There are twelve pairs of feet (500*,®), a pair to each segment situated between the head and 
penultimate uromere or abdominal segment; these, with the caudal pair of appendages, make in all 
thirteen pairs of legs. 

The number of arthromeres or body-segments is sixteen, counting the head as consisting of two 
when seen from above, and the telson as a rudimentary arthromere, so that there are thirteen 
arthromeres between the head and telson, each of them bearing legs. There is no apparent dis¬ 
tinction, as regards the segments themselves, into cephalothorax and abdomen (urosome), but there 
are two cephalic, nine thoracic segments, and seven abdominal, counting the telsou as the seventh. 
The first seven pairs of (thoracic) legs are much alike in appearance, reminding us of those of Peta- 
lophthalmus and Gnathophausia; these are succeeded by five pairs of abdominal appendages, which 
are about half as long and large as the thoracic legs. The first pair of thoracic legs (which do not 
seem to be mandibular palpi) are considerably larger (broader and longer) than the succeeding 
ones. It is composed of six joints ; the first and second rather narrow ; the third broad, with, ac¬ 
cording to Meek and Wortheu, “ three” spines on the “ under side” (these were not to be seen in 
my specimens, though undoubtedly existing there); fourth longer than the third, with three spines; 

1 Before going to press I received from Mr. Lacoe a very large specimen, his No. x*, m which are two large smooth 
concavities, one on each side of the base of the head ; it is possible that these are sessile eyes. 








ON THE SYNCARIDA. 


125 


fifth joint thicker than the fourth, thickening towards the distal end, with four spines, the fourth 
spine the largest and as long as the joint is tiiick ; the sixth about two-thirds as thick as the fifth, 
with two remote spines on the under side and ending in two spines, one of them very large and 
stout (there is possibly a third small spine). In Meek and Worthen’s figures the spines are errone¬ 
ously drawn on the outer side of four joints; we find that the spines are situated only on the two 
penultimate joints; the terminal claw is not represented by Meek and Worthen. The succeeding 
six pairs are all about the same size and length, being large, well developed, long, and slender, 
about one half to two-thirds as thick as the first pair (406'’), with no traces of a gill; the second 
pair are a little stouter than the others and apparently spined on the penultimate joint; the sev¬ 
enth jjair the slenderest and nearly as long as the first pair; the three basal joints are long and 
slender, the third very distinct, long, and slender; fourth joint long, slightly swollen in the mid¬ 
dle; fifth equal to the sixth in length, but slender, slightly thickened towards the distal end; the 
sixth somewhat longer than the fifth, ending in a point; none of the terminal joints appear to be 
chelate. 

The abdominal appendages are distinctly biramous and schizopodal in their appearance. Each 
apparently consists of a small, narrow, jointed limb and a larger exopodital branch (or gill(?); see 
406“’’’). We can see traces of the first two pairs. In another specimen (50L®’'’) the first three pairs 
of abdominal legs are to be plainly seen ; the exopodital or respiratory and swimming ramus is 
sessile, lanceolate-oval, and broad, thickened on the hinder (?) edge. In Mr. Carr’s specimen No. 
1 are distinct traces of a biramous appendage on the fourteenth and fifteenth (penultimab*) seg¬ 
ments ; and in his No. 3 there are to be seen the traces of the second-fourth pairs of abdominal feet, 
with double rami, the hinder ramus the smaller and narrower. In an abdominal foot (in Lacoe’s 
No. 406P’S) the second joint is narrow, lanceolate-oval, rounded at the tip, from which arise a series 
of long slender setm, about twelve in number, which form an oar-like appendage equaling in size 
the basal joint; total length of the limb 14.5“’'“ (the basal joint 8'“™, the row of set® 6.5'““ = 14.5'““). 
These legs remind us somewhat of those of Squilla, as do the first thoracic pair, from their being 
larger than the others and armed on the under side with stout spines. 

The telsoii is very long and slender, narrow, acute, the end very slender, with long setre on 
each end ; it is a little longer than the caudal feet (uropoda) on each side of it. The caudal feet, 
or sixth pair of uropoda, are divided into two long, large, acute rami (endopodite and exopodite) 
arising from a small, short basal joint (Carr’s No. 1). The two rami are of nearly the same size 
and length, both edges of each branch being setose (the setae are not so numerous and close as 
represented in Meek and Worthen’s figure). 

Of forty specimens examined, the total length of the largest example, including the caudal 
appendages, but not including the antennae, was 75““ (Lacoe’s No. 58““); another still larger 
(No. x^) was 85““ in length; a specimen received from Mr. Carr was 58““ in length. 

In a specimen of A. eveni, 45““ in length, I made the following measurements: Width of 
the body, 6-7"”" (in Lacoe’s 501'’: Width of first cephalic segment, 5.5'""’; of second segment, 6"”"; 
length of first and second head-segments together, fi'"-"; length of rostrum, 1"’-"; length of sixth seg¬ 
ment, 3.5"”"); length of first antennae, about 12"”"; length of second antennae,26"""; length of first jaair 
of feet, 20''""; greatest width of fifth joint of first feet, 2"""; length of abdominal feet, 18-19"”"; length 
of telson, 13"”"; length of caudal appendages, 12""". 

Many of the specimens are preserved flattened out, showing the back, with the legs spread 
out symmetrically on each side; others are preserved lying on their side, with the body somewhat 
arched, and then they present a shrimp-like appearance, though on a superficial examination 
reminding one of an Amphipod lying on its side. 

The foregoing remarks apply to the larger specimens described by Meek and Worthen as 
Acanthoiehon eveni. I cannot with certainty point out any distinctions from A. stimpsoni M. & W., 
the first-described species; the smaller specimens, which might be referred to the latter species, 
are evidently the young of A. eveni il. and W. Hence the specific name should be Stimpsoni. 

The characters of this Crustacean are such as to forbid our referring it to any known group; 
we therefore suggest that it forms the type of a suborder of thoracostracous Crustacea, which we 
would designate as the Syucarida. 

What we should regard as the difierential characters of the group Syucarida, to which Acantho- 


126 


MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 


telsou belongs, are the sixteen free segments of the body, which are hoinonomoiis or of uniform 
size, the first and second, however, being soldered together; the absence of a true carapace; the 
seven pairs of schizopod-like legs, the first pair, spined and raptorial, slightly reminding one of 
those of Squilla; the second pair also spined; the antennas of both pairs are long and slender, the 
two flagella of the first pair being very unlike any sessile-eyed or edriophthalmatoiis Crustacean ; 
the six pairs of abdominal feet, which are long, slender, and with a general resemblance to those 
of the Schizoi^oda; the broader, oar-like swimming ramus, ending in long setae. Any doubts as to 
the macrourau affinities of the Syncarida are removed by an examination of the long, acute telson 
and last pair of abdominal appendages; the appendages are biramous, the divisions flattened from 
above downwards, so that they with the telson serve, as in schizopods and shrimps, for propelling 
the body backwards when the animal is disturbed. 

We should regard the Syncarida as the lowest group or suborder of Thoracostraca, but much 
nearer the Schizopoda than the Cumacea; they form a connecting link between the Amphipoda and 
Thoracostraca, but at the same time in their most essential characters stand much nearer to the Schi¬ 
zopoda than the Amphipoda; the lack of a carapace, even a rudimentary one, and the homonomous 
segmentation, causing them to bear a resemblance to the Edriophthalma, which they would not 
otherwise present. The Syncarida may be regarded as the homotoxial equivalents of the Decapoda, 
Schizopoda, or Stomapoda. To the Isopoda, Acanthotelson presents a superficial resemblance, due 
to the slightly vertically compressed body and the homonomous segmentation. The Edriophthalma 
(Arthrostraca of some late authors) are defined by Claus as “ Malacostraca with lateral sessile 
eyes, usually with seven, more rarely with six or fewer separate thoracic segments, and the same 
number of pairs of legs, without a carapace,” but this definition does not express those differences 
in the form of the antennte, the thoracic legs, and abdominal appendages, especially those of the 
end of the urosome or abdomen, which are characteristic of the sessile-eyed Crustacea as distin¬ 
guished from the Thoracostraca. 

From the Isopoda, in which the body is usually broad and vertically flattened, with seven free 
thoracic segments, while the abdominal legs are lamellar and closely appressed to the short abdo¬ 
men, our Acauthotesou plainly differs in the long bi-flagellate Decapod-like first antennie, in the 
long homonomous segments of the abdomen, and the schizopodal abdominal feet, and especially the 
Schizopod-like telson and last pair of feet, adapted, as in the shrimps, for striking the water from 
above downw’ards. 

The Amphipoda are, in general, characterized by their laterally compressed body, with lamel¬ 
late gills on the thoracic feet, and an elongated abdomen, of which the three anterior segments 
bear the swimming feet, while the three posterior bear posteriorly-directed feet, adapted for 
springing (Claus). Now, if Acanthotelson is not an Isopod, still less should it be regarded as 
related to the Amphipoda. The first anteume are entirely unlike those of any known Amphipods, 
the latter having a very short accessory flagellum; the second antenmn of Acanthotelson are 
strictly decapodous in appearance and very different from those of the Amphipoda, whfereas in 
Gammarus the scape is as long as the tiabellum. Although there are seven free thoracic segments 
in Acanthotelson as well as in Gammarus and other Amphipoda, those of Acanthotelson are not 
compressed any more than in the Schizopoda, and there are no traces of epimera; on the contrary, 
the free edges of the thoracic and abdominal segments are much as in the Schizopoda and Caridea. 
The thoracic appendages of Acanthotelson are, on the whole, like those of the Stomapoda and 
Schizopoda. We cannot detect any traces of mouth-parts, mandibles with their palpus, or maxillm; 
but the thoracic legs do not present any close resemblance to those of the Amphipoda, the first 
pair being as much, if not more, like those of Squilla than any Amphipod with which we are 
acquainted, while the three posterior pairs, which are in form and size like those in front, entirely 
differ from those of Gammarus and most other normal Amphipods, in which the basal joint is very 
large and triangular. Turning to the abdomen, the diflerence in that of Acanthotelson from that 
of the Amphipods is still more marked. The first five pairs of uropoda, or abdominal appendages, 
are, in Acanthotelson, all formed apparently on the same plan, not essentially different from those 
of Schizopods, while the last pair are flat and on the same pbme as the telson and intimately asso¬ 
ciated with the latter; in short, these parts are formed on a truly niacrurous plan and most approach 
those of the Schizopods, in which the telson and rami of the last pair of feet are narrow and more 


ON THE SYNC ARID A. 


127 


or less acute at the end. There is nothing in the structure of the urosoine and its uropoda in 
Acanthotelson to remind us of the same parts in the Amphipoda. 

Excluded from the sessile-eyed Crustacea, and forced to place Acanthotelson in the Thoracos- 
traca, we are confronted by the lack of a carapace and the homonomous segmentation of the body. 
These are essential fundamental characters, but still the nature of the appendages and telson is 
such as to forbid us from rejecting the Syncarida from the ordinal limits of the Thoracostraca. 
We are compelled, therefore, to regard the group as a suborder standing near or at the base of the 
Thoracostraca, not far from the Stomapoda and Schizopoda, and with appendages closely homol¬ 
ogous with those of these two groups. The Syncarida, from their lack of a carapace, and from the 
well-formed dorsal arch of the seven thoracic segments, we are obliged to consider as an annectant 
or synthetic group, pointing to the existence of some extinct group which may have still more 
closely connected the sessile-eyed and stalked-eyed Crustacea. 

Notice of Acanthotelson ? magister (n. sp.). 

PI. II, Figs. 4,5. 

' I have received from Mr. J. G. Carr, for examination, a specimen from Mazon Creek, collected 
at the same place as the nodules containing the Acanthotelson, showing the remains of a crustacean 
closely similar to, if not generically identical with Acanthotelson. Unfortunately the head and auten- 
nrn are not preserved sufficiently well for description, so that the following account should be regarded 
as provisional, until better-preserved specimens are found. As seen by the photograph (PI. II, fig.s. 
4, 5), the animal was of the same general shape as in Acanthotelson; when it died the body was 
curved on itself, so that the two longer antennae crossed the end of the abdomen with its append¬ 
ages. The abdomen in its dorsal aspect, with the telson and last pair of uropoda, are tolerably 
well preserved. The faint traces of the head, unless we are mistaken, show that it was of the 
same general shape as in Acanthotelson. There are traces of two pairs of autennm; one fragment, 
the innermost, showing traces of six joints; and there are faint impressions, not showing the joints, 
of two long auteiinm, which are about half as long as the body. There are no traces of any thoracic 
or abdominal appendages except the last pair of uropoda. 

Description. —Body very broad, being nearly twice as broad as the largest Acanthotelson eveni, 
M. & \V. The penultimate abdominal segment is a little more than one-half as long as the terminal 
segment. The last segment is very large and square, the sides nearly even, not narrowing poste¬ 
riorly, and it is the broad square shape of this segment which will readily enable one to separate 
it from the previously described species of Acanthotelson. The telson is stout, broad at the base, 
and rather short, much shorter than the uropoda appended to the same segment. The terminal 
uropoda are broad and stout, with no traces of setae. The basal joint is broad, triangular, but a 
little longer than broad ; the outer ramus is of moderate length, ensiform, and slightly longer than 
the telson; there is only a fragment of the inner telson left in the fossil, which, however, shows 
that it was considerably narrower and smaller than the outer i)air. 

Probable length of the whole body, not including the antennae or telson, 70"'"’. 

Length of penultimate abdominal segment, 5"“". 

Breadth of penultimate abdominal segment, 12'"“. 

Length of terminal abdominal segment, 10'"“. 

Breadth of terminal abdominal segment, ll*"™. 

Length of telson, 10'"'"; breadth at base, 2'"'". 

Length of basal joint of last pair of uropoda, 4'"'"; breadth, 3.5'”'". 

Length of outer ramus of last uropod, 11'"'"; breadth, 2""". 

Explanation of Plate I. 

Fig. 1. Acanthotelson stimpsoni M. & W., restored, enlarged twice. 

Fig. lo. Acanthotelson stimpsoni M. & W., head and antennaj seen from above, enlarged twice. 

Fig. 16. Acanthotelson stimpsoni M. & W., first thoracic leg Xf. 

Fig. Ic. Acanthotelson stimpsoni M. & W., sixth thoracic leg xf. 

Fig. Id. Acanthotelson stimpsoni M. & W., telson and last pair of uropoda Xf. 

Fig. 2. Acanthotelson f magister Pack., Xf. All the figujes drawn by Dr. J. S. Kingsley. 


128 


MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 


Explanation of Plate lx. 

Fig. 1. Acanthotelson sliinpsoni M. *fe W. 

Fig. 2. Acanthotdson stimpsoni M. & W., reverse of fig. 1. 

Fig. 3. Acanthotelson stimpsoni M. & W. 

Fig. 4. Acanthotelson ? maf/ister Pack. 

Fig. 5. Acanthotelson ? magister Pack., reverse of fig. 4. 

From i)botograpIis taken by Mr. Robert L. P. Mason. 

jVbfe on an additional specimen. —Since this memoir was sent to the printer I have received a larger specimen from 
Mr. Lacoe, labelled “P>raidwood, Ill., Q'”, which, exclusive of the antennai and telsou, measures about 82™“. There 
are traces of four pairs of thoracic feet which are long and slender and bent backwards from the head, reminding us 
of the four hinder legs of an ordinary shrimp seen from one side. There are traces of the antennm, better preserved 
than in the original specimen. There appear to be a pair of large antenme, the scape composed of three large joints, 
the second and third smaller and together equalling in length the basal joint; these antennae appear each to bear a 
large antennal scale, re.sembling those of the Macrura, and reaching as far as the middle of the third antennal joint. 
The characters shown by this specimen lead me to refer it to a genus distinct from Acanthotelson, for which the 
the name Belotelson (the entire name, Belotelson magister) is proposed. Additional specimens are much desired to 
complete our knowledge of its affinities. 




MEMOIRS NAT ACADEMY SC.,VOL III PLATE I 





J.S Kingsley.aei. juiiut. Bien 4 Co. Iith 


FIGS.l-|d ACANTHOTELSON STIMPS0Nli2 A? MAGISTER 



















PLATE II 


MEMOIRS NAT. ACAD SC. VOL III 



FIGS. 1 -3. ACANTHOTELSON STIMPSONI; 4. 5. A? MAGISTER 


FROM photographs BY R. L- P. MASON 






















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II.-ON THE GAMPSONYCHIDJ], AN UNDESCRIBED FAMILY OF FOSSIL 
SCHIZOPOD CRUSTACEA. PL. Ill, FIGS. 1-4; YII, FIGS. 1, 2. 

BEAD APRIL 21, 1855. 


By A. S. Packard. 


The opportunity of examining at my leisure about a dozeu specimens of Palceocaris typus of 
Meek aiul VVorthen. kindly afforded me by Messrs. K. D. Lacoe and J. 0. Carr, has enabled me to 
work out some characters of this genus not mentioned by the original describers. The study of 
these specimens has induced me to compare the genus with Grampsouyx, and the result has led to 
the formation of a family or higher group for the genera, which should probably stand at the base 
of the Schizopoda, while also serving to bridge over the chasm existing between the Thoracostra- 
cous suborders, Syncarida and Schizopoda.* 

Palieocaris was first described by Messrs. Meek aud Worthen, in the Proceedings of the 
Academy of Natural Sciences of Philadelphia (1865, p. 48), from specimens occurring in clay-stone 
concretions in the lotver part of the true coal measures, at Mazon Creek, Morris, Grundy County, 
Illinois. Afterwards, in the third volume of the Reports of the Geological Survey of Illinois, 1868, 
the same authors figured the fossil, aud expressed themselves as follows regarding its affinities: 
“Hence it would seem to present something of a combination of decapod (macrourau) and tetra- 
decapod characters. Tliat is, it possesses the caudal appendages, anteriorly directed thoracic legs, 
theantennm (some of the specimens appear, also, to show basal scales to the outer autennae) aud 
general aspect of a macrourau, with the distinct head, divided thorax (without a carapace), and seven 
jiairs of thoracic legs, of a tetradecapod. We have not been able to see its eyes, but from its other 
decapod characters, aud its analogy to Gampsoiiyx, which is said by von Meyer to have pedun¬ 
culated, or at any rate movable, eyes, we are strongly inclined to believe that our fossil will be 
found to agree with Gampsouy.x in this character also. 

“It therefore became a matter of interest to determine to which of the subclasses, Decapoda or 
Tetradecapoda, it really belongs. That it belongs rather near Gampsonyx, though not to the same 
subordinate section (Schizopoda), there can be little doubt. Hence these two forms apparently fall 
naturally into the same family. Professors Jordan aud vou Meyer seem to have regarded Gamp¬ 
sonyx as a Tetradecapod, connected with the Amphipoda, but also possessing macroural decapod 
aftinities. Professor Dana, however, regards it as a low type of Macrura, belouging to the section 
Schizopoda. He and Dr. Slimpson, to whom we sent sketches of our better specimens of Palmo- 
caris, concur in the opinion, judging from all its characters yet knowu, that it is a low embryonic 
type of the Macrura, iu which the carapace is not developed. 

iWe Dave not seen Bnrmeister’s memoir “ Ueber Garapsonychas” (Abh. d. naturf. Ges. iu Halle, ii, IDl, 1855), 
but Zittel (Handbuch der Palieoutologio, p. G70) quotesBurmeisteras stating that he regarded it “as the representa¬ 
tive of a special group of Crustacea, which unites in itself some of the mo.st esseutial features iu the organization of 
the Stomapoda and Amphipoda.” 

S. Mis. 154-17 


129 






130 


MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 


“Generically, it is separated from Gampsonyx, figures of which (cuts C and D) we have added 
for comparison, not only in the nature of its caudal appendages, but in the more important char¬ 
acter of having its thoracic legs simple, and not bifid, as in the Schizopoda.” 



Fig. 1.—Gampsonyx fimbriatus. After Jordan and von Meyer. From Meek and Worthen. 

We will now describe in detail Palwocaris typus, restoring it so far as possible in our description 
from the specimens received from Messrs. Lacoe and Carr, amounting in all to about a dozen, of 
which ten were kindly loaned by Mr. Lacoe. Dr. Kingsley has also obligingly drawn a restoration 
of the fossil from the specimens sent him for the purpose. There are no traces of a carapace, but 
the head is plainly distinct from the rest of the body. It is rounded in front, with no traces in my 
specimens of a rostrum, and is apparently composed of two segments. The body, seen .sidewise, is 
suddenly arched or bent at the articulation of the thoracic and abdominal regions, as in stoma, 
pods and shrimps, and of the usual proportions. All the segments behind the head are free, and 
are fourteen (seven of which are abdominal) in number, counting the telson as one. There are 
thus sixteen segments, the head composed of two, the thorax of seven, and the abdomen of seven. 
The body thus has apparently the same number of thoracic and abdominal segments as in the 
existing Stomapoda. It is probable that the head of Palccocaris is composed of the same number 
of segments as in the Schizopoda, but as the mouth parts have not been preserved, this i)oint must 
remain undetermined. The thorax, in its general shape, as seen from above, is of the normal shape, 
as seen in existing Stomapoda. The abdomen is much narrower than the thorax, with the basal 
segments short, and the penultimate one longer than broad, widening out a little on the hind margin, 
and excavated behind to receive the base of the telson. 

The first antennae are about one-half as long as the body, with the scape long and slender, 
three-jointed (unless what I regard as the basal joint consists, as appearances suggest, of two); 
first joint long and slender; second, as thick but only one half as long as the first; third, moder¬ 
ately long, considerably longer than the second; flagella nearly equal in size, long and slender. 

The second antennm with the scape three-jointed, the basal joint long; second and third, of nearly 
the same size and length; flagellum thick at base, long and slender, entire antenna nearl 3 ’ half as 
long as the body of the animal. 

Of the thoracic feet, six pairs can be detected, while in front of the first pair are two other 
appendageslikethelegs, but whether they are gnathopods, like those of other Schizopoda, or thoracic 
feet, it is difiBcult to judge. Each thoracic foot is long and slender, the three distal joints forming 
the greater part of the limb. The terminal (geventh ?) joint is very long and slender, and probably 
ends in a single claw. The penultimate joint is about two-thirds as long as the terminal. It is 
thickened towards the end, and is perhaps a little shorter than the third joint from the end. 

The endopodites* are distinctly preserved ; those on the last four pairs of legs are long, narrow, 
lanceolate-oval, acute at the end, each side of the endopodites being alike, i. <?., one not being more 
convex than the other. If extended, the endopodite would reach out to near the middle of the 
terminal joint of the limb. I think I can detect eight pairs of endopodites—six at least—one on 
each thoracic leg and one on each of the gnathopods, if such they are. This would tend to show 
that the first two appendages behind the head are true gnathopods, like tho.se of existing Schizo- 
pods, esi)ecially Petalophthalinus. 

There are traces of a pair of abdominal legs to each of the seven segments. To the rather 

*I had regarded these appendages as breeding lamellae, but Dr. Kingsley suggests that they are endopodites, and 
though the joints are very industinct, I am disposed to accept his correction, and will speak of them as endopodites. 
We should, on general grounds, regard them as endopodites 








|ON THE GAMPSOmrCHIDiE. 


131 


thick and long basal joint of each[were probably attached two slender rami. The entire limbs 
were about one-half as long as the thoracic legs (see Lacoe’s No. 404®f). There were at least five 
pairs (and I think traces ot a sixth) besides the last pair. The end of the abdomen, with the telson, 
and last pair of legs are as described and figured by Meek & Worthen. The telson is large in 
size, broad and short, somewhat triangular, being broader at the base than at the end. It is some¬ 
what spatulate in torm, being well rounded at the end, and much shorter than the inner rami of the 
appendages associated with it. Its end is fringed with coarse setae. In the last abdominal ap. 
peudages, the outer ramus is broader than the inner, with a deep longitudinal crease, or impressed 
line, which fades out on the outer third, or extends to the end of the basal joint. The second, or 
distal joint, is tringed with fine setae. The suture between the two joints is externally indicated by 
two setae larger than the others, and somewhat curv'ed. The inner ramus is somewhat shorter than 
the outer j the end well rounded, and fringed with setae. It reaches to the second joint of the 
longer outer ramus. 

Total length of the largest specimen 33““. 

Total length of the best preserved specimen 25““ (Lacoe^s No. 404®^). This specimen gave us 
the following measurements : 

Length of Ist antennae (estimated) 8“™. 

Length of 2d antennae (estimated) 10-11““. 

Length of last thoracic leg (exopodite) 8““. 

Length of endopodite 4““. 

Length of telson 3““; width 1.5““. 

Length of outer ramus of last pair of abdominal feet 4““. 

It should be observed that the eudopodites are in part represented in Meek and Worthen’s 
figure, but not referred to in their description. They are also partly represented in their copy of 
Jordan and von Meyer’s figure of Gampsonyx Jimbriatus. In the latter, there is also present what is 
apparently a large, coarsely spined, mandibular palpus, somewhat like that in the male of the exist¬ 
ing deep-sea Schizoiiod Petalophthahmis armatus described by Willemoes-Suhm.* In the females 
however, the palpus is small and unarmed. In the figure of Gampsonyx referred to, the thoracic 
legs themselves, irrespective of the endopodites, are represented as biramous, and the two rami are 
drawn as of nearly equal length. It is probable that there has been a mistake in drawing the 
legs, as in none of the existing Schizopods, such as Mysis and its allies Euphausia, Gnathophausia, 
Petalopthalmus or Chalaraspis, are the legs thus thrice divided. It is to be hoped that the fossil 
itself will be examined anew with regard to this important point.t 

It is sufliciently evident, however, that Gampsonyx and Palmocaris are closely allied forms, and 
as first suggested by Messrs. Meek and Worthen should fall into the same family, which may be 
called Gampsonychidse. The principal character which separates this group from all other Schizo¬ 
pods is the entire absence of a carapace. 

It is worthy of notice, however, that the size of the carapace is very variable in the Schizopods, 
and in the genus Petalophthalmus there is a great discrepancy in the two sexes. In the female it 
covers the entire thorax, while in the male it is remarkably small, subtriangular, leaving the two 
hinder thoracic segments entirely exposed, as well as the sides of the two segments in front. In the 
large size and ^oval-lanceolate shape of the endopodites, both of the guathopods (maxillipedes) 
and thoracicfeet, theGampsonychidm'agree with Petalopthalmus, in which they are large and broad. 
In the shape of the telson and the comparative size and proportions of the last pair of abdominal 
appendages there is a close relationship in the Gampsonychidse to the Schizopod genera Petalo¬ 
phthalmus and Chalaraspis, especially the latter genus, in which the telson is rounded at the end, 

* _ ___ ____ __ 

* On some Atlantic Crustacea from the Challenger Expedition, by Dr. R. von Willemoes-Suhm. Linnaean Trans¬ 
actions. Zoology, vol. i, p. 23, 1874. 

tNo light is thrown on the nature of the limbs by the thirty specimens of Palceocaris scoticus described by Mr. 
B. N. Peach from the lower Carboniferous rocks of Scotland. Nor were eyes with certainty detected in his specimens. 

“ For instance, although in most of the specimens there occur small oblong bosses just in the place where their eyes 
should be, were tliey decapods, figs. lO-lOd, yet the facets of the cornea have been looked for in vain. This is unfor¬ 
tunate, as it prevents one from saying with certainty that these are the eyes, though there is a strong presumption in 
favor of their being so. No sessile eyes have been observed on the carapace, neither has a trace of anything been 
observed that could be construed into such.”—Trans. Roy. Soc. Edinburgh, 1882, p. 86. 




132 


MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 


while the two rami are more as in Petalophthalmus, though broader. The other biramous abdominal 
appendages in the Gampsonychidce are truly schizopodal. 



Fio. 3.—^Petalolphthalmus armatnecT. 



Fig, 4.—Petalophthalmns armatus $. This and Fig. 3 after W. Suhm. 



Fig. 3a.—Telaon of Peta- 
lophthlamuscT. 




Fig. 46.—Third 
pereiopod of Peta¬ 
lophthalmus $. 


Classifying the Schizopoda by the carapace, modifying Willemoes-Suhm’s table by throwing 
out the Nebaliadae and substituting the Gampsonychidae, there would seem to be three groups, as 
follows: 


I. Carapace absent.(Gampsonychidae). 

II. Carapace free, varying in size.(Gnatbophausia, Petalopthalmus and Cbalaraspis). 

III. Carapace fastened to tbe thorax.(Mysis, Lophogaster and Enphausia). 

But I should agree with Willemoes-Suhm that this is not a natural genealogical classification, 
and throwing out the Nebaliadte, which, as we have endeavored to show, belong to a distinct order 
of Crustacea, the families of Schizopods may be enumerated thus (after adding the Gampsonychidae 
to von Suhm’s table), all having seven abdominal segments: 


Carapace absent, six pairs of thoracic legs. 

Carapace well developed, six pairs of thoracic legs... 
Carapace well developed, eight pairs of thoracic legs 
Carapace well developed, four pairs of thoracic legs. 
Carapace well developed, seven jiairsof thoracic legs. 


..I Gampsonychidae. 
.II Mysidae. 

III Euphausiidae. 

IV Chalaraspidae. 
.V Lophogastridae. 


When we compare the Gampsonychidre with the Syncarida (Acanthotelsou), we see that both 
groups have the same number of body-segments, and that both lack a carapace; and thus, while 
the Gampsonychidae are the ancestors of living Schizopods, the group as a whole probably de- 























ON THE GAMPSONYCHID^. 


133 


scended from Acanthotelson, which is thus a truly synthetic form, standing in an ancestral relation 
to all the Thoracostraca, while it also suggests that the sessile-eyed and stalked-eyed Crustacea 
may have had a common parentage. 


Explanation of Plate III.* 

Fig. 1. Palwocaris typiis, M. & W. restored, enlarged four times. (The front of the head is partly conjectural 
and though stalked eyes probably existed, no attempt has been made to restore them.) 

Fig. 2. PaJwocaris hjpus, seven thoracic segments, showing the disposition of the eiTdopodites, X? (Lacoe’s 4046). 
Fig. 3. Palceocaria typus, dorsal view of one side of three thoracic segments, showing the basal joints of the en- 
dopodites (endop), and exopodites (exop), enlarged. 

Fig. 4. Palceocaria typua, telson and last pair of uropoda. X?. 


All the figures on this plate drawn by Dr. J. S. Jtingsley. 









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^ylEMOIRS NAT ACADEMY SC.,VOL III 


PLATE III 



^ _ ^ ■■ ■ ~~ 

J.S.Kingsley,del. Julius Bien & Co.lilh 


PAL/EOCARIS TYPUS. 

























m.-ON THE ANTHRACARIDil, A FAMILY OF CARBONIFEROUS MACRU- 

ROUS DECAPOD CRUSTACEA. 

READ APRIL 21, 1885. 


By A. S. Packard. 


Having been kindly favored by Messrs. E, D. Lacoe and J. C. Carr with the opportunity of 
examining their collections of nodules from Mazon Creek containing Antlirapalcemon gracilis Meek 
and Worthen, I have been able to discover some features jirobably not sliowii in the specimens 
examined by Messrs. Meek and Worthen. The newly observed characters are the carapace with 
its rostrum, showing that the American sjiecies in these respects closely resembles the European 
ones figured by Salter, the founder of the genus. Moreover, our specimens prove the existence of 
five pairs of thoracic legs, while the antennse of both pairs are almost entirely shown. The fact 
that the first pair of thoracic feet were scaicely larger than the succeeding pairs, suggests that 
Anthrapalaemon cannot be placed in the Eryonidie, but should form the type of a distinct group of 
family rank, none of the existing Macruia, so far as we are asvare, having such small anterior 
legs. Other characteristics which we ahall point out confirm this view. 

The genus Anthraiialiemon, a Carboniferous fossil, was first described by J. W. Salter in the ♦ 
Quarterly Journal of the C-eological Society of London, (xvii, 529, 18G1). The name given to the 
fossils has, the author remarks, “only a general signification, and is not intended to indicate a 
real relation to Pahiemou.” He also remarks that “the genus is not to be confounded with any of 
the Liassic or Oolitic ones published by von Meyer, Miinster, «&c. . . . It is broader than the 

general form of the Astacidse, or than Glyiihcea and its Liassic allies, but much narrower than EryonJ^ 
Salter’s type siiecies is Anthrapaloimon grossarti Salter.* With this species the American A. 
gracilis is congeneric. A closely allied English form, A. clubius Prestwich, is referred by Mr. Salter 
to the subgenus Palmocarabus, a name even less fitting than Anthrapalaemon. Concerning the 
other form provisionally referred to Anthrapalemon by Mr. Salter (his Fig. 5), we will remark 
in a supplementary note to this article. 

The only American species we have seent is Anthrapalcemon gracilis Meek & Worthen, first 
described in the Proceedings of the Academy of Natural Sciences of Philadelphia, 1865, and 
redescribed and figured iu the second volume of the Geological Survey of Illinois, and again in 
the third volunie. 

Mr. Salter figured the carapace and rostrum, as well as the abdomen of the European species ; 
while the specimen figured by Meek and Worthen evidently did not possess the carapace, but 
showed perfectly the telson and neighboring pair of abdominal api)eudages. 

The specimens loaned us by Mr. Lacoe enable us to give a more perfect description and illus¬ 
trations of this important type; and 1 am indebted to Hr. J. S. Kingsley lor the restoration and 

* Iu his Handbuch der Paheoutologie, Zittel mentions Pseudogalathea Peach, from the carboniferous of Scotland. 

We have not yet seen Mr. Peach’s article. 

tDr. J. W. Dawson has described and figured, the carapace of Anthrapalcemon hillianum, from the Carboniferous 
of Nova Scotia. Geol. Mag., iv, new ser., p. 56, fig. 1, 1877. Also figured iu his Acadian Geology, 1878. 

135 








136 


MEMOIES OF THE NATIOl^AL ACADEMY OF SCIENCES. 


details, which he has so faithfully drawn. I am inclined to think that the body was actually 
broader than Dr. Kingsley has drawn it, and that the lateral spines of the carapace were visible 
from above; but I leave it as an open question. 

The carapace is of the same length as the iirosome (abdomen) or slightly longer, being from 
two-thirds to three-fourths as wide as it is long. It is very thin and delicate, and many specimens 
have none. The sides are regularly curved, and unarmed behind the middle, but on the anterior 
third are seven distinct, sharp lateral spines, the seventh being three times as large as the others 
and situated on the anterior outer angle of the carapace. I cannot with certainty distinguish any 
spines between this last-mentioned spine and the rostrum.* Casts of the latter are distinctly seen 
in two specimens (Lacoe’s 200pp and 20i)mm) to be small, triangular, short, and acute. The 
rostrum itself is pretty well preserved in one specimen (Mr. Lacoe’s No. 200i>). It is rather long, 
stout, strong, acute, situated between the lirst auteniife, and extending as far as the uiiddleof the 
third joint of the scape of the latter. In another specimen (Lacoe’s 200oo, 20(hi/r) the rostrum is 
fairly well preserved; it is long find slender, and about half as long as the carapace; also as long 
as the abdomen is wide in its narrowest part. 

In only a single specimen is a side view of an apparently folded carapace preserved. The 
entire rostrum is long and straight, slender and acute, originating in the anterior third of the 
carapace, the entire rostrum being about half as long as the carapace itself. (PI. VII, figs. 3. 3a.) 

Along the sides are numerous sharp spines. Whether there was, as in the other form (A. 
grossarti), a series of dorsal spines our specimens do not distinctly show. Behind the base of the 
rostrum a median ridge extends to the posterior edge of the carapace. The lower edge of the 
carapace is serrate on the anterior third, as in all the other specimens. On the surface of the 
carapace an apparently false or superficial suture i)asses out laterally from the anterior third, and 
another impressed line, better marked, from the posterior third, extending half-way to the edge 
of the carapace. The surface of the carapace is seen to be finely shagreened, but scarcely" tuber- 
culated, as in the European A. grossarti. 

Of eyes no traces are visible in any of the specimens excei)t one, and I am inclined to the 
opinion that they Avere either wanting or very small, and concealed under the front edge of the 
carapace. At the same time it should be obserA'cd that in none of the fossil macrurous Crustacea 
from the Carboniferous are the eyes preserved. It may also be borne in mind that in the deep- 
sea seulpius S iiith no corneal area was to be detected, and in Willemoesia and the fossil 

Eryoniscus the eyes are entirely wanting.! So far as we can decide, the front edge of the carapace 
is not excavated at the i)oint where we shouki look for eyes or eye-stalks, but, on the contrary, 
seems to be quite regularly convex. Still, additional specimens are needed to clear up the exact 
nature of the front edge of the carapace. 

In most of the specimens the thin, delicate carapace has not been preserved. When it is 
absent the five thoracic segments are distinctly marked, of about the same length. In front of 
these are three cephalic segments, making eight segments in all apparent in some specimens. 

The first antenme are large and long; the sca[)e three jointed, first joint long, the second about 
one-half as long as the first and of about the same width; third joint a little longer, but smaller, 
than the second; the two fiagella are a little longer than the scape, the inner one about half as 
thick and evidently only half as long as the outer one. (Lacoe, No. 200//.) 

The second antenme are, with the scape, considerably stouter than those of the first pair; first 
joint short and stout, but longer than broad; second very short, oblique at the end, and consid¬ 
erably shorter than the third joint, which is about as long as thick; the fiagellum is A^ery long and 
slender, multiarticulate, at least as long as the carapace, and directed backward, as in Peutacheles; 
there is an antennal scale present, but its outlines are very indistinct. 

The five pairs of legs are preserved (Nos. 200^p, 200"*"'); they are all of nearly equal size, the 
first pair apparently being no larger than tiie others, in this resjiect differing from Galathea and the 
existing Galatheidea. Of the first pair of limbs there are in one specimen (200d) traces of nearly 

• Dr. Kingsley has, however, detected a spine at ihis point and inserted it in his drawings, as seen in the plate. 

t After this paper was written the specimens were sent to Dr. Kingsley to be drawn ; among them the specimen 
with traces of an eye. He has drawn in the eye ; and on examining the specimen again, I think that he is right in 
representing the eyes. It was apparently large and well developed. 






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Fig. 7 .—Anoplotus j oUtus Smith. 


x' IG. 6a .—Eumunida picta, end of abdomen enlarged. 


1506 

Fig. 5 .—jrunida valida Smith. 


1503 

Fig. e.—Evmnnida picta Smith. 


Recent beep-sea Galatheidea. After S. I. Smith. 


S. Mis. 154—To face page 137. 




















ON THE ANTHRACAEID^.. 


137 


the entire limb, i. e., at least the first and second joints; the third joint could not have been of 
large size, a feature distinguishing the Eryouidre as well as Astacidae and the higher Macrurans 
in general. The first and fifth pair seem to be of about the same size; the third aud fourth pair 
of legs are a little larger than the others and but little longer than the width of the carapace, ft 
is untortunate that no specimens have yet been found with the first pair of limbs entire, but the 
fact that the two basal and perhaps the third joints are no larger than those of the other pairs of 
feet indicates that this form dilfered from all the fossil and recent Eryouidte, and is a character of 
so much importance as to forbid our regarding Authrapahemon as a member of that family; the 
only other alternative being to consider it as a type of a distinct family. Of the four hinder pairs 
of legs the three terminal joints of the limbs (these affording the diagnostic characters) are pre¬ 
served, and the proportions are much as in the four hinder i)airs of thoracic legs of the existing 
deep-sea Pentacheles; of the three joints the proximal and middle ones are long and slender, the 
inner one longer than the outer of the two; the distal (terminal) joint is rather short and pointed, 
and ai)parently chelate. Meek and Worthen remark that the legs are not divided; whether they 
meant that the legs are not divided as in the Schizopoda, or simply referred to the terminal joint 
alone, does not appear, but in the specimen before us (No. 200pp) the last joint ai)pears to be 
chelate, since what seems to be the smaller inner finger is partly but tolerably well preserved, the 
crust or derm itself being preserved. Yet we may be mistaken.* In Meek and Worthen’s figure, 
the terminal joints are drawn as undivided. If this is the case, they resemble the four hinder 
legs of Munida, Eumunida, and Auoplotes. 

The abdomen is rather short aud broad, as in the Galatheidic, aud consists of seven segments, 
counting the telson as the seventh. 

The general appearance and relative size of the telson, together with the last pair of abdominal 
appendages, is much as in the Eryonidm, with some important differences. The telson, unlike that 
of any other Macruran, fossil or recent, so far as I am aware, is differentiated into three portions; 
the basal central piece is somewhat polygonal, a little longer than broad; it is separated by a 
distinct suture from a small triangular terminal piece which forms the ai)ex of the telson. Between 
tbe outer half of the entire telson and the inner ramus of the uropoda is a large broad lobe which 
is fringed with setse. At first I regarded it as a subdivision of the inner lobe of the last uropoda or 
abdominal feet, but no instance among the Decapoda is known to us in which the last pair of 
uropoda have more than two lobes or divisions, and I have therefore been inclined to associate the 
innermost of the three setiferous lobes with the telson, and to regard the telson as divided into 
two median and two lateral lobular setiferous portions. Whether the two lobes belong with the 
telson or uropoda I will leave for the present an open question. The only group in existence in 
which the telson is so remarkably differentiated is the Galatheidm. In Munida the telson is 
divided by sutures into four pieces, the two terminal ones lobate aud edged with seta? of the same 
size as those of the uropoda. In Eumunida of Smith the telson is “short and broad, more or 
less membranaceous, aud divided by a transverse articulation, so that the distal part may be 
folded beneath the basal part.” In Anoplotm politus. like the foregoing, a deep-sea Galatheid, 
“the telson is stiffened by eight distinct calcified plates; a broad median basal plate, with a small 
one on either side at the base of the uropod, aud a small median one behind it, and between a pair 
of broad lateral plates, still behind which there is a second pair, which meet in the middle line and 
form the tips and lateral angles.” Professor Smith’s figures of Munida, Eumunida, aud Anopotus 
are here rein-oduced from electrotypes kindly loaned by Professor Baird, U. S. Fish Commission.t 

From the nature of the differentiation of the telson in the Galatheidm I am inclined to believe 
that the telson of Anthrai)ahemon is subdivided in somewhat the same manner. If so, we cannot 
refer the genus to the Eryonidm, and we would therefore regard it as the type of a distinct family 
which may thus be briefly characterized : 

Family AnthracarUhv: Body rather broad aud slightly tiattened ; first antenme with two long 

* Ill none of the six Scottish Carhoniferoiis species of Anthrapalienion described by Mr. B. N. Peach, do either of 
the thoracic limbs appear to be chelate. 

t Preliminary report on the Hrachyiira and Auomura dredged in deep water off the south coast of New England, 
by the U. S. Fish Commission, in ld80. By S. I. Smith, Proc. U. S. Nat. Museum, 1883, June 18. 

S. Mis. 154-18 


138 


MBMOIES OF THE NATIOI^AL ACADEMY OF SCIENCES. 


flagella ; second antenuie long, without a scale ; the first pair of thoracic legs no longer than the 
four succeeding pairs ; the fifth pair of legs as long and well developed as the others ; carapace 
ovate, smooth, without transverse impressed lines, with a long, acute rostrum; with lateral spines 
on the anterior half; abdomen rather broad, nearly as much so as the carapace; the telsou broad 
and differentiated into two median pieces, the basal piece with broad, rounded membranaceous 
lobes, one on each side, fringed like the two rami of each uropod, with long seta?. 

After the foregoing paper was written, and an abstract published in the American Naturalist 
for September, 1885, I sent the specimens to Dr. Kingsley to be drawn, and on their return he 
made the following criticisms, which are here quoted : 

“ From the characters shown in the specimens before me, Anthrapalffiinou apparently has 
nothing to do with the Eryonidm, but belongs rather to the Schizosomi of Stimpson. The thoracic 
structure, antennm, sternum, and telsou are all paralleled in that group. The telsou is much like 
tKat of the Porcellaiu crabs. The absence of the distal pedal joints of the legs renders its family 
uncertain. It may belong to some of those existing in the fauna of to-day. It certainly shows no 
features which would justify the creation of a new familj’ for it.” 

While I should hardly agree with the view that Anthrapalmmon belongs to the Schizosomi, 
since Porcellana is a brachyuran, with abroad, round cephalothorax and small abdomen, 
folded beneath the body, the differentiation of the telson is somewhat as in Porcellana, 
as will be seen by reference to Fig. 7, copied from Milne Edwards.* O n the other hand, I 
have erred in regarding it as closely allied to the Eryonidfe, as defined by Zittel in his 
Handbuch der Palaeoutologie. Having already drawn attention to the highly differen- Fig.7.— 
tiated telsou of the Galatheidte, 1 am now much inclined to regard the Anthracaridfe Abdonien 
as more nearly related to this group. The resemblance to the Galatheidje is seen in the Porcel- 
general shape of the body, the proportions of the carapace with its sharp rostrum, and ^ 
the proportions of the abdomen with its broad telson and uropofla. The first pair of auteumc differ, 
however, from those of the Galatheida? in having two well-developed flagella, and the first pair of 
legs are much smaller, while the fifth pair are larger in proportion; the last pair of uropoda are 
more as in the Glyphaeidfe and Astacida?, the outer ramus being divided into a long basal and short 
broad distal segment. 

It seems to us, from what we now know of the characters of Anthrapalfemon, as we have 
worked them out, that it cannot be placed in any known family of Decapoda. We should now be 
inclined to place the Authracaridie nearest the Galatheidfe, most of which are deep sea forms. 
It is not improbable that they were the forerunners or ancestors of the Galatheid;e.t That the 
family is a synthetic group is shown by the resemblance of its telson to that of Porcellana, a 
Brachyuran. It certainly does not belong among the Palinuridie, nor, on the other hand, among 
the Glyphfeidae. 

In ZittePs valuable Handbuch' der Paljeontologie (Bd. 1, 2d Abth., Lief, iv, p. 682), Anthrapa- 
laemon is placed among the Peumidie, but its characters appear to be such as to forbid such an 
alliance. Palaeontology is an inexact science, but the attempt to seek the natural position of 
extinct forms leads us to examine their remains more closely, to make further explorations for 
more perfectly preserved specimens, while the final result is to lead us to enlarge our concep¬ 
tions as to the affinities of existing types of life. It seems to us better to establish new groups for 
Palaeozoic forms of uncertain positions than to crowd them into groups of highly specialized 
modern forms. Yet this tendency ■tay be carried too far. Whether we have erred in the present 
instance we leave to the judgment of those who, with a special knowledge of modern Crustacea., 
also possess both critical skill and broad views in dealing with natural groups. 

Note on the Palaeozoic Shrimps {Carididce). 

The form provisionally referred to Anthrapalaemon by Salter (liis fig. 5, Quart. Journ. Geol. 
Soc. Loudon, xvii, 1861), occurring in the Carboniferous beds at Lanarkshire, Scotland, which has 

" Crustac^s, pi. 22, tig. 7. 

t After writing the foregoing remarks I found I had overlooked Professor Dana’s opinion, expressed on p. 350 of 
his Manual of Geology, 3d edition, where, after referring to the British species of Anthrapaheraou, he adds, “ but the 
broad flattened cajapax indicates a nearer relation to Alglea and Galathea than to Palsemon.” 






I 




ON THE ANTHEACAKID^. 139 

been copied into geological text-books as representing Anthiapalsemon (see Dana’s Manual of 
Geology, fig. 686 A), does not belong to that genus or the group it represents, but is evidently 
one of the true shrimps or Carididae. The carapace and serrated rostrum, as well as the shape of 
the abdomen, the form of the last pair of uropoda, and the telson, all indicate genuine prawn-like 
affinities. It may be named Archicaris salteri. 

I'he other Carboniferous shrimps are Crangopsis soliates (Salter, Quart. Journ. Geol. Soc. 533, 
fig. 8, 1861). This appears to be a genuine Caridid; it is from the subcarboniferous beds of 
England. (As synonyms of Crangopsis Salter are Palceoarangoti Salter, non SchatTroth, and Ifro- 
7iectes Salter. (See Zittel’s Palmontologie.) 

PggocepJialus cooperi, of Huxley, from the Carboniferous beds near Manchester, England, is a . 
doubtful form, which he refers “either to the decapodous or stomapodous group of the class.’ 
(Quart. Journ. Geol. Soc., xiii, 363, 1857; xviii, 420, 1862). Professor Dana (Manual of Geology, 

3d edit., p. 350) regards this form as a Schizoj)od. 

No Carboniferous Carididm have as yet been discovered in America. The oldest known 
macrurous Crustacean, however, is American, the PalwopaUemon newberryi, described by ]\Ir. Whit¬ 
field (Amer. Journ. Sc., 33, 1880), from the Upper Devonian of Ohio. 

Explanation of Plate IV. 

Fijf. 1. Antkrapaliemon (jraciliH, M. & W., restored, enlarged 3 times. 


2. 

< ( 

6i 

it 

carapace and eyes, X f- 

3. 

il 

U 

ti_ 

carapace flattened, seen from above x 3^. 

4 

li 

a 

ti 

part of first thoracic leg, X f. 

5. 

iC 

u 

it 

four basal joints of tlie fifth leg, X 

6. 


It 

it 

telson and last pair of nroiioda, X t to f. 


All the figures on this plate drawn by Dr. J. S. Kingsley. 



- 

ftjv. I y 



e* 




s'-t./ ll-.U 




J.S.Kingsley, del. 


Julius Bien A Co.ltlh 


ANTHRAPAL/EMON GRACILIS. 
























0 020 205 641 6 


